1. Field of the Invention
The present invention pertains to the management of sequence counters used in communications protocols, and more particularly, to the management of sequence counters whose values are retained in non-volatile storage.
2. Art Background
Numerous communications protocols use sequence counters. As an example, Internet security architectures such as the IPSec suite of protocols use monotonically increasing counters to deter replay attacks, an attack where a message is captured and resent intact to the receiver with the hope that a previous action or state will be duplicated.
In such protocols using sequence counters, both the sender and receiver must maintain the last value received to use in comparison to newly received messages. When a new message is received and validated, the sequence counter value is incremented. In current implementations of such protocols, when a power failure or other unplanned restart occurs, security protocols are re-negotiated from scratch using techniques which are expensive in terms of computation and time required. After such re-negotiation, communications under the protocol proceed.